Battery a bit low.

About 2 weeks ago i went mudding with my jeep and after i returned hom i cleaned everything with the garden hose, including my engine bay. During the last few days my jeep has been harder than usual in starting, i originall attributed this to being due to the fact it hasnt been driven for a few days. The battery guage on my cluster shows about 12 volts (engine off), which always in the past has been 13-14. Once i get the engine started it jumps back to 13volts. Today using a multimeter i measured the battery with the engine off to be at 12.3 volts. I am a bit worried and need to try to see if anything is abit unnormal here.

thanks
pete

did you get the tps wet? it doesn't like water.

Cheer it up!

12.6VDC is "nominal" for most batteries - but it can range from 12.2VDC to about 13.4. Going off of the panel gage won't fly - it's a notorious liar, and should only be used for "relative state of charge" rather than an absolute reading. Back it up with a decent DVM.

TPS being wet will affect acceleration and mileage (to an extent,) but it will have little effect on starting.

What year? RENIX is a little more prone to "hard start/long cranking" than HO, and that's useful to know...

It's possible to get water/mud/crap intrusion into the OEM cables, since the ends aren't sealed, and that can also cause trouble.

And, check to make sure your CPS sensor connection (should be near the rear end of the fuel rail) is clean, since contamination there will cause hard starting as well...

5-90

94 XJ 4x4 4.0 Auto

Here is what i have done already, maybe this can be of help.

I have checked for bad grounds by using a multimeter on the positive end of the bat and used the negative end of the multimeter to test on diff areas of the engine and they all pretty correspond with no more than .01 variance of voltage. So it isnt likely its a bad ground problem.

I have cleaned TPS and CPS connectors.

I have aired out the alternator with an air compressor, not much came out.

Not sure if this is meaningful but with the engine off, and the multimeter connected to the battery terminals i tried diff loads. Starting voltage ~12.5V, Headlights on brings it to 12.1, Vents/fan high on in additon brings it to 11.8V.

Thanks for the replies , hope this helps a bit.

pete

Mudding can stretch the belt, have you checked it?

Belt is at proper tention .

pete

Sound like the battery is low on amps. After sitting around my XJ's battery runs a little low on them and will start hard too. Putting the battery on the charger usually solves it for me. Your battery may have a cell going bad. Try doing a gravity test on the batteries cells. If the cells are all good try charging it up to 100% capacity using a good charger. This will at the very least eliminate the battery as the source of the problem and you can work out from there to solve the problem. Just my $.02. Good luck.

Your advice makes a lot of sense...Do u think i should take it to get tested at autozone tommorrow ?

pete

jeepsrock said:

Your advice makes a lot of sense...Do u think i should take it to get tested at autozone tommorrow ?

pete

Click to expand...

Try this - put a DVM on the battery terminals, and have a helper crank the starter. Batter voltage should not drop below 9.6VDC - if it does, you're starting to get "sulphation" on the plates (spongy lead coated with lead sulphate - interfered with the generation of electricity) and it's time to think about getting a new battery. Disable the ignition and crank for 10-15 seconds.

I've had to use those testers (probably the Bear ARBST, right?) and I don't have much faith in them... Besides, there's a reason they make those testers relatively "idiot-proof" - it's so the kid who just started to shave last week doesn't have to think when he's trying to use it...

5-90

(Dammit - hit "quote" instead of "edit" again...)

Well 5-90 without reading your response this morning i took the battery for testing at my local kragen , he hooked up a small handheld gadget to the battery and entered the battery CCA and performed a test which took a few min. I really doubt the validity of a test like that to, but it said my battery was 100% health.

One thing i noted that was interesting was that after i drove the jeep to the auto place i used the multimeter to test the voltage with the engine on and it was 13.9V, pretty much all loads i could run didnt bring it down past 13.8V. When i got home and it turned it of the voltage was 13V, but moments later it began to drop to where it normally settles at ~12.5V . Is this normal within 10-15min ?

As far as your test how do i stop the ignition ? Is thier a fuse ?

pete

Stop the ignition either by removing the coil wire to the distributor, removing the coil primary wire (the smaller 12VDC wires,) or by disconnecting the DC connectcor to the coil rail or removing the coil rail entirely (2000-2001XJ.)

From a quick read of what you've done, looks like your alternator is just fine, and it's normal for a battery to have a slight "surface charge" that dissipates within a few minutes of shutting down.

Settling down to ~12.5VDC is nominal, but it's the application of a load that we're interested in. Since you probably don't have a "load box" (I've had one for years - applies a 300A load to the battery...) you can use the next best thing - which is the starter. Those little testers are so crammed with electronics that you can't fit much in the way of a resistive load in them, and they don't like head (and my load box gets HOT.)

DO NOT crank your starter for more than about 15 seconds - you could end up overheating the start motor (and wind up having to replace it as well.) 15 seconds is plenty of time - and allow at least 5 minutes between tests, if you decide to run it more than once (so the start motor windings can cool down.)

I worked at Kragen when they rolled out the Bear ARBST tester for the first time - I kept bringing my load box and DVM to work anyhow, because it gave me more useful results. I'm a bit leery of "GO/NOT GO" results on anything that isn't purely mechanical - doubly so on electrics.

5-90

Load testing it is cool for testing all the cells but I've found using a hydrometer can pinpoint you to a problem with a specific cell. Sounds like the a cell is bad or shorted due to sulphation as 5-90 said. This will drain the stored capacity down quickly but it may still pass the load test.

Having a battery like thats going on the fritz will make you alternator work extra hard trying to keep it charged. This will burn out the diodes in the alternators regulator. Get a battery hydrometer to do a gravity test on the electolite in all the cells. About $5 and they look like this:
http://www1.acehardwareoutlet.com/(txljp4mculsmgwb1cf1p0b45)/ProductDetails.aspx?SKU=80530&Source=froogle

Also here a link I keep on how to do the test with a hydometer or a voltmeter and a coat hanger:
http://autorepair.about.com/cs/electrical/a/aa121000b_2.htm

If the battery checks out then you'll have to start looking at the wiring with with a ohm meter. Hopefully it's just the battery. Digging for a shorted - or + wire in the engine bay sucks.

Good luck :confused1. Here's some more battery links for you edumacation.
http://www.ehow.com/how_5923_check-rv-battery.html
http://www.uuhome.de/william.darden//index.htm
http://www.uuhome.de/william.darden//carfaq4.htm

Thanks for all the advice but something happened today that might change all this direction of thinking.

Tonight i was gonna use the jeep to return a DVD rental and the engine would not turn at all. As i turned the key all th guages did their thing but not one sound from the engine. The first thing i tried was switching the fan relay to the starter one - still no go. I checked all the fuses and no go. Picked up the multimeter checked voltage ~12.3 V , i guess thats ok.

I remembered a while back reading or seeing that when one experiences starter problems they can usually get it to start by giving it a few good wacks with a hammer. I got under the jeep and gave it a few good hard wacks, put the key in and it started (a bit hard but it started).

I am thinking that the starter is bad, would this be the case ? I was under the impression when a starter dies it makes weird noises or something , but this one does absolutly nothing until i hit it.

??? Thoughts

Thanks
Pete

Good idea whacking the starter with the hammer! Sounds like the started solonoid that kicks the starter gear out to the flywheel is shot. No noise, no click, nothing. Hitting it with the hammer must've got it loose for you again. I had a 73' Pinto that had this problem once. Good luck getting it out and taking it to the auto parts for testing. Sounds like you got this one solved. :yelclap:

Def sounds like a bad starter to me.

Over all, it sounds like either your battery is suffering from excessive internal leakage (high resistance short), or there's a high resistance short in your electrical system that's slowly draining your battery while setting overnight.
Your "at rest" voltage of 12.5 is a little low for a battery just charged; however, standard regulators will not fully charge a battery during a short drive. The 13.8 volts read while the engine was running indicates your alternator's regulator is working normally; it's just at 13.8V's it takes forever to bring a battery up to full charge. A fully charged battery (used, but in good shape) should have an "at rest" voltage of 12.65--any thing less indicates inability to take and hold a full charge. !2.2v indicates a battery at 50% charge, so you can see there's a very narrow spread between "discharge" and "charge". Try isolating the battery by charging through extended trip (hopefully will see 12.6V at rest), then disconnecting the battery overnight; should still be at 12.6 in the morning. If it reads less than 12.5 in the morning, get a new battery. If it's OK in the morning, you have something on, or a high resistance short in you electrical system.

Hey Xj bubba ...read the last post update by me...wouldnt that change your mind ? I realy think its the starter now.

Plus a question for everyone, i can get the unit rebuilt locally for aout 65$ or pick up another one form napa for 110$. I am thinking the rebuild, plus he gives a 1yr warranty with it.

? Thanks
pete

jeepsrock said:

Thanks for all the advice but something happened today that might change all this direction of thinking.

Tonight i was gonna use the jeep to return a DVD rental and the engine would not turn at all. As i turned the key all th guages did their thing but not one sound from the engine. The first thing i tried was switching the fan relay to the starter one - still no go. I checked all the fuses and no go. Picked up the multimeter checked voltage ~12.3 V , i guess thats ok.

I remembered a while back reading or seeing that when one experiences starter problems they can usually get it to start by giving it a few good wacks with a hammer. I got under the jeep and gave it a few good hard wacks, put the key in and it started (a bit hard but it started).

I am thinking that the starter is bad, would this be the case ? I was under the impression when a starter dies it makes weird noises or something , but this one does absolutly nothing until i hit it.

??? Thoughts

Thanks
Pete

Click to expand...

Sounds like you've probably got some loosening in the solenoid contacts (it happens...) or a loose connection internally. Once a starter is cleaned up and works, there's nothing that should cause the solenoid plunger to "stick" (unless you're dealing with a MASSIVE rear main leak, which can throw a load of oil into the nose housing of the starter...) so most failures tend to be electrical - brushes or contacts.

5-90

12.3v is basically a discharged battery. In addition, the ole hammer routine is about as shade-tree as you can get--especially with starter motors that use ceramic magnets . That's a very good way to destroy the starter motor.